ISSN:
1432-1017
Keywords:
Key words Cytolysin
;
Hemolysis
;
Alcohol
;
Fatty acid
;
Membrane permeabilization
;
Lipid vesicles
;
Anesthetics
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Physics
Notes:
Abstract Equinatoxin II, a 19.8 kDa pore-forming toxin from the sea anemone Actinia equina, was examined for hemolytic activity and permeabilization of small unilamellar lipid vesicles (SUV) in the presence of increasing amounts of n-alcohols (methanol to n-octanol) and fatty acids (palmitic and palmitoleic acid). We observed an enhancement of toxin activity which was dependent on the concentration of the membrane partitioning additive. An exception was palmitic acid which exerted a bimodal role. While at low bulk concentrations it increased toxin-induced hemolysis, above 3 µM bulk concentration it was inhibitory; in neither case was it efficient in promoting release of the fluorescent marker calcein from SUV. The increased permeabilization activity was correlated with an increase in the amount of toxin bound as indicated by changes in the intrinsic toxin fluorescence. In the case of n-alcohols, at least, these effects appeared to depend on the actual amount of alcohol present inside the membrane rather than on its specific chemical nature. This suggests that the observed effects could be due to changes of the biophysical properties of the lipid bilayer, such as thickness, lipid acyl-chain ordering, and dielectric constant induced by the partitioned additives.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s002490050027
Permalink